DESCRIPTION: (from applicant's abstract): Heterologous prime/boost immunization using DNA priming and recombinant MVA boosters have proved to raise much higher levels of T-cell responses than either of these modalities of immunization alone. The goals of this program project are to develop and evaluate the cross-clade activity of DNA/MVA protocols for immunodeficiency virus vaccines. The charges for Project 1 are to provide DNA and MVA immunogens for the preclinical and clinical trials supported by Projects 2 and 3. Two major goals for Project 1 are to develop immunogens that increase the efficiency of DNA priming and MVA boosters and to construct immunogens that allow evaluation of cross-clade responses. To increase the immunogenicity of vaccine DNAs, plasmids will be optimized for expression in the presence of interferons (IFN), and vaccine inserts will be codon optimized. Both clade A and clade B immunogens will be built to facilitate the analysis of cross-clade responses. A team of Emory, CDC and NIAID investigators will accomplish Project 1. Drs. Smith, Robinson, and Boss (Emory) will be responsible for the construction of the DNA immunogens, Dr. Moss (NIAID) will be responsible for the construction of MVA immunogens, and Dr. Folks (CDC) will provide clade A sequences and conduct safety tests.